Flange facing of Check valve

[babyfatface]

The wording of the check valve spec reads:

"... Flange end-Raised Face per ASME B16.5, standard 3.2/6.3 Ra flange facing finish per ASME B46.1, ASME16.34, API594 ...."

The flange facing is required to be serrated raised face.

I am asking if the above spec clarifies the face to be serrated.

Thanks.

 

[JimCasey]

Sounds like a smooth finish to me. Serrated flanges have roughness in the 125-250 range. 3.2-6.3 is slick as nasal exudate on a portal fastener. BUT more significantly your spec should say "Serrated Gasket Surface". AND there are phonograpic (spiral)serrations OR (expensive) Concentric grooves.

Smooth surfaces are used for Flexitallic-type spiral-wound gaskets. Serrated flanges are used with rubber or composition gaskets. The spiral of a Flexitallic usually does not match the spiral of the serration, so you get the hard spots of the gasket perched up on the high spots of the flange serrations with likely leakage.

 

[DRE111]

ASME16.34 only calls out the B16.5 flanged fitting requirements for valve flanges. B46.1 is a spec on characterizing surface finish, and API-594 is a check valve spec.

3.2 - 6.3 micrometers (125 - 250 micro inches) Ra with concentric or spiral serrations is the standard flange facing called out in B16.5 for raised face flanges. This finish only applies only to the gasket contact surface.

 

[ecsprocurement]

It just means Flanged Raised face ends. The Ansi specs are the same for the flange in itself.